Apparatus for providing a multi-mode interface between a baseband receiver and radio frequency circuitry

ABSTRACT

An apparatus for providing a multi-mode interface between a baseband receiver and radio frequency (RF) circuitry. According to a preferred embodiment of the invention, the apparatus includes a first differential-to-single-ended converter, a second differential-to-single-ended converter and an analog-to-digital converter. The first differential-to-single-ended converter receives an incoming differential current pair to be converted into a first single-ended voltage signal. The second differential-to-single-ended converter receives an incoming differential voltage pair to be converted into a second single-ended voltage signal. Further, the analog-to-digital converter selectively receives an incoming single-ended voltage signal, the first single-ended voltage signal, or the second single-ended voltage signal to be converted into a digital signal to be further processed by the baseband processor. Note that the incoming single-ended voltage signal, as well as the incoming differential voltage and current signal pairs together form the multi-mode interface to the RF circuitry.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a regular application and claims the benefit ofpriority from U.S. provisional patent application Ser. No. 60/397,181filed Jul. 19, 2002, which is also related to a copending applicationentitled “Apparatus for Providing a Multi-mode Interface between aBaseband Transmitter and Radio Frequency Circuitry”, U.S. patentapplication Ser. No. ______, filed ______.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to wireless communications. More particularly, theinvention relates to an apparatus for providing a multi-mode interfacebetween a baseband integrated circuit and a radio frequency integratedcircuit.

2. Description of the Related Art

Traditionally, a baseband integrated circuit (IC) may only be connectedwith a radio frequency (RF) IC through a fixed interface. As illustratedin FIG. 1A, RF circuitry 120 has an interface to transmit and receivesingle-ended voltage signals to and from baseband circuitry 110. Thebaseband circuitry 110 provides a corresponding interface to transmit asingle-ended voltage signal 130 to the RF circuitry 120, and to receivea single-ended voltage signal 131 from the RF circuitry 120. Referringto FIG. 1B, RF circuitry 122 has an interface to transmit and receivedifferential voltage signals to and from baseband circuitry 112. To workwith the RF circuitry 122, the baseband circuitry 112 provides acorresponding interface to transfer differential voltage signal pairs132 and 133 with the RF circuitry 122. Turning now to FIG. 1C, basebandcircuitry 114 provides an interface to transmit a pair of differentialcurrent signals 134 to RF circuitry 124, and to receive a pair ofdifferential current signals 135 from the RF circuitry 124. Hence, theRF circuitry 124 must have a corresponding interface to receive andtransmit differential current signals.

However, a conventional baseband IC with a fixed interface, which, asdescribed above, will lack freedom in the choice of an appropriate RFIC. The conventional baseband IC also suffers from difficulty inreplacing an existing RF IC with other types. Therefore, what is neededis a baseband IC, especially, a baseband receiver incorporating amulti-mode interface to flexibly connect a wide variety of types of RFcircuitry, unencumbered by the limitations associated with the priorart.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus forproviding a multi-mode interface between a baseband receiver and radiofrequency (RF) circuitry.

The present invention is generally directed to a baseband receiverconnected with RF circuitry which translates the spectrum of RF signalsback to a lower frequency for baseband processing. According to oneaspect of the invention, the apparatus includes adifferential-to-single-ended converter and an analog-to-digitalconverter. The differential-to-single-ended converter takes an incomingpair of differential signals and outputs a converted single-endedsignal. The analog-to-digital converter selectively takes an incomingsingle-ended signal or the converted single-ended signal, and outputs adigital signal to be further processed by the baseband receiver. Thus,the incoming single-ended signal and the incoming differential signalpair together form the multi-mode interface to the RF circuitry, inwhich these signals are selectively allowed to input from the RFcircuitry.

According to another aspect of the invention, the apparatus includes asingle-ended-to-differential converter and an analog-to-digitalconverter. The single-ended-to-differential converter takes an incomingsingle-ended signal and outputs a converted pair of differentialsignals. The analog-to-digital converter selectively takes an incomingpair of differential signals or the converted pair of differentialsignals, and outputs a digital signal to be further processed by thebaseband receiver. Hence, the incoming single-ended signal and theincoming differential signal pair are provided to form the multi-modeinterface to the RF circuitry.

In one embodiment of the present invention, the apparatus includes ananalog-to-digital converter, two differential-to-single-ended convertersand multiple input terminals. A first input terminal is provided toreceive an incoming single-ended voltage signal. Second and third inputterminals are provided to receive an incoming pair of differentialvoltage signals. Further, fourth and fifth input terminals are includedto receive an incoming pair of differential current signals. A firstdifferential-to-single-ended converter is coupled to the fourth and thefifth input terminals to receive the incoming pair of differentialcurrent signals as a first input pair. The firstdifferential-to-single-ended converter is configured to convert thefirst input pair into a first single-ended voltage signal for furtherconversion. A second differential-to-single-ended converter is coupledto the second and the third input terminals. The seconddifferential-to-single-ended converter receives the incoming pair ofdifferential voltage signals as a second input pair. It converts thesecond input pair into a second single-ended voltage signal for thefollowing conversion. The analog-to-digital converter is coupled to aparallel connection of the first input terminal, the first and thesecond differential-to-single-ended converters. The analog-to-digitalconverter selectively receives the incoming single-ended voltage signal,the first single-ended voltage signal, or the second single-endedvoltage signal as a third input. It is used to convert the third inputinto a digital signal to be further processed by the baseband receiver.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described by way of exemplary embodiments,but not limitations, illustrated in the accompanying drawings in whichlike references denote similar elements, and in which:

FIGS. 1A˜1C are block diagrams illustrating RF ICs with commonly usedinterfaces to connect corresponding types of baseband ICs in accordancewith the prior art;

FIG. 2 is a block diagram illustrating a baseband receiver with aninterface conversion module of the invention;

FIGS. 3A˜3P are basic building blocks for the interface conversionmodule in accordance with the invention;

FIGS. 4A˜4D are block diagrams illustrating four structures that can beused to implement the interface conversion module in accordance with theinvention;

FIG. 5 is a block diagram illustrating a first embodiment of theinvention;

FIG. 6 is a block diagram illustrating a second embodiment of theinvention; and

FIG. 7 is a block diagram illustrating a third embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 illustrates a block diagram of a baseband receiver 200 accordingto the invention. To establish a multi-mode interface between a basebandIC and a RF IC, an interface conversion module 220 is provided toconvert various signal modes into digital signals. The interfaceconversion module 220 offers the RXV and RXI inputs to respectivelyreceive a single-ended voltage signal and a single-ended current signal.The interface conversion module 220 offers the RXV+ and RXV− inputs toreceive a pair of differential voltage signals, and also offers and theRXI+ and RXI− inputs to receive a pair of differential current signals.On some occasions, RF circuitry may offer a digital signal translatedfrom an analog signal at RF. Therefore, the RXD input of the basebandreceiver 200 is available to bypass the interface conversion module 220in order to directly receive such a digital signal. As depicted, digitalsignal processor (DSP) 210 receives the digital signals from theinterface conversion module 220 via line 212. The DSP 210 serves as abaseband processor and outputs processed data over line 202 for furtheroperations. It should be appreciated that the interface conversionmodule 220 is well suited for both in-phase (I) and quadrature (Q)components of baseband signals.

According to the invention, the interface conversion module 220 can beimplemented with the following basic building blocks. For brevity, thesebasic components illustrated in FIGS. 3A˜3P are divided into fivecategories. The first category encompasses four types ofanalog-to-digital converters (ADCs). TYPE 1 shown in FIG. 3A is asingle-ended voltage input ADC. TYPE 2 shown in FIG. 3B is adifferential voltage input ADC. TYPE 3 shown in FIG. 3C is asingle-ended current input ADC. TYPE 4 shown in FIG. 3D is adifferential current input ADC. The second category refers tosingle-ended-to-differential converters (SDCs) which convert asingle-ended signal into a pair of differential signals. TYPE 1 shown inFIG. 3E is a single-ended voltage input and differential voltage outputSDC. TYPE 2 shown in FIG. 3F is a single-ended current input anddifferential voltage output SDC. TYPE 3 shown in FIG. 3G is asingle-ended voltage input and differential current output SDC. TYPE 4shown in FIG. 3H is a single-ended current input and differentialcurrent output SDC. The third category pertains todifferential-to-single-ended converters (DSCs) which convert a pair ofdifferential signals into a single-ended signal. TYPE 1 shown in FIG. 3Iis a differential voltage input and single-ended voltage output DSC.TYPE 2 shown in FIG. 3J is a differential current input and single-endedvoltage output DSC. TYPE 3 shown in FIG. 3K is a differential voltageinput and single-ended current output DSC. TYPE 4 shown in FIG. 3L is adifferential current input and single-ended current output DSC. Thefourth category includes two types of voltage-to-current converters(VCCs) which convert a voltage signal into a current signal. TYPE 1shown in FIG. 3M is a single-ended input and single-ended output VCC.TYPE 2 shown in FIG. 3N is a differential input and differential outputVCC. The fifth category contains two types of current-to-voltageconverters (CVCs) which convert a current signal into a voltage signal.As illustrated in FIGS. 3O and 3P, TYPE 1 is a single-ended input andsingle-ended output CVC, and TYPE 2 is a differential input anddifferential output CVC, respectively.

Using these basic components, the interface conversion module 220 can beimplemented with four structures. Referring to FIG. 4A, the firststructure is a parallel form. In this form the selected basic componentsare connected in parallel, and the possible configurations for theparallel form are listed here in TABLE 1. Referring to FIG. 4B, thesecond structure is a cascade form. In this form the selected basiccomponents are connected in cascade, and the possible configurations forthe cascade form are listed here in TABLE 2. Referring to FIG. 4C, thethird structure is a hybrid form I. In this form, as depicted, theselected basic components are connected in a combination of parallel andcascade forms, and the possible configurations for the hybrid form I arelisted here in TABLE 3. Turning now to FIG. 4D, the fourth structure isa hybrid form II. In this form, as depicted, the selected basiccomponents are connected in a second combination of parallel and cascadeforms, and the possible configurations for the hybrid form II are listedin TABLE 4 below. With respect to FIGS. 4A˜4C as well as TABLES 1˜4,note that block A is representative of the ADCs, and Blocks B, C and Dare selected from the other categories of the basic building blocks. Itshould be understood that any suitable permutations and combinations ofthe basic components are contemplated to implement the interfaceconversion module 220 by the principles of the invention. TABLE 1 A B CD 1 TYPE 1 ADC TYPE 1 CVC TYPE 1 DSC TYPE 2 DSC 2 TYPE 2 ADC TYPE 1 SDCTYPE 2 SDC TYPE 2 CVC 3 TYPE 3 ADC TYPE 1 VCC TYPE 3 DSC TYPE 4 DSC 4TYPE 4 ADC TYPE 3 SDC TYPE 2 VCC TYPE 4 SDC

TABLE 2 A B C D 1 TYPE 1 ADC TYPE 1 DSC TYPE 2 SDC TYPE 4 DSC 2 TYPE 1ADC TYPE 1 CVC TYPE 3 DSC TYPE 2 CVC 3 TYPE 1 ADC TYPE 2 DSC TYPE 2 VCCTYPE 2 SDC 4 TYPE 1 ADC TYPE 1 DSC TYPE 2 CVC TYPE 4 SDC 5 TYPE 1 ADCTYPE 1 CVC TYPE 4 DSC TYPE 2 VCC 6 TYPE 1 ADC TYPE 2 DSC TYPE 4 SDC TYPE3 DSC 7 TYPE 2 ADC TYPE 1 SDC TYPE 1 CVC TYPE 4 DSC 8 TYPE 2 ADC TYPE 2SDC TYPE 1 VCC TYPE 2 DSC 9 TYPE 2 ADC TYPE 2 CVC TYPE 3 SDC TYPE 1 CVC10 TYPE 2 ADC TYPE 1 SDC TYPE 2 DSC TYPE 4 SDC 11 TYPE 2 ADC TYPE 2 SDCTYPE 4 DSC TYPE 3 SDC 12 TYPE 2 ADC TYPE 2 CVC TYPE 4 SDC TYPE 1 VCC 13TYPE 3 ADC TYPE 1 VCC TYPE 1 DSC TYPE 2 CVC 14 TYPE 3 ADC TYPE 3 DSCTYPE 1 SDC TYPE 2 DSC 15 TYPE 3 AUC TYPE 4 DSC TYPE 3 SDC TYPE 1 DSC 16TYPE 3 ADC TYPE 1 VCC TYPE 2 DSC TYPE 2 VCC 17 TYPE 3 ADC TYPE 3 DSCTYPE 2 CVC TYPE 3 SDC 18 TYPE 3 ADC TYPE 4 DSC TYPE 2 VCC TYPE 1 SDC 19TYPE 4 ADC TYPE 3 SDC TYPE 1 DSC TYPE 2 SDC 20 TYPE 4 ADC TYPE 2 VCCTYPE 1 SDC TYPE 1 CVC 21 TYPE 4 ADC TYPE 4 SDC TYPE 1 VCC TYPE 1 DSC 22TYPE 4 ADC TYPE 3 SDC TYPE 1 CVC TYPE 3 DSC 23 TYPE 4 ADC TYPE 2 VCCTYPE 2 SDC TYPE 1 VCC 24 TYPE 4 ADC TYPE 4 SDC TYPE 3 DSC TYPE 1 SDC

TABLE 3 A B C D 1 TYPE 1 ADC TYPE 1 DSC TYPE 1 CVC TYPE 2 CVC 2 TYPE 1ADC TYPE 1 DSC TYPE 2 DSC TYPE 2 SDC 3 TYPE 1 ADC TYPE 1 CVC TYPE 2 DSCTYPE 3 DSC 4 TYPE 1 ADC TYPE 1 CVC TYPE 1 DSC TYPE 4 DSC 5 TYPE 1 ADCTYPE 2 DSC TYPE 1 DSC TYPE 4 SDC 6 TYPE 1 ADC TYPE 2 DSC TYPE 1 CVC TYPE2 VCC 7 TYPE 2 ADC TYPE 1 SDC TYPE 2 SDC TYPE 2 DSC 8 TYPE 2 ADC TYPE 1SDC TYPE 2 CVC TYPE 1 CVC 9 TYPE 2 ADC TYPE 2 SDC TYPE 2 CVC TYPE 1 VCC10 TYPE 2 ADC TYPE 2 SDC TYPE 1 SDC TYPE 4 DSC 11 TYPE 2 ADC TYPE 2 CVCTYPE 1 SDC TYPE 4 SDC 12 TYPE 2 ADC TYPE 2 CVC TYPE 2 SDC TYPE 3 SDC 13TYPE 3 ADC TYPE 1 VCC TYPE 3 DSC TYPE 2 DSC 14 TYPE 3 ADC TYPE 1 VCCTYPE 4 DSC TYPE 1 DSC 15 TYPE 3 ADC TYPE 3 DSC TYPE 4 DSC TYPE 1 SDC 16TYPE 3 ADC TYPE 3 DSC TYPE 1 VCC TYPE 2 CVC 17 TYPE 3 ADC TYPE 4 DSCTYPE 1 VCC TYPE 2 VCC 18 TYPE 3 ADC TYPE 4 DSC TYPE 3 DSC TYPE 3 SDC 19TYPE 4 ADC TYPE 3 SDC TYPE 2 VCC TYPE 1 CVC 20 TYPE 4 ADC TYPE 3 SDCTYPE 4 SDC TYPE 1 DSC 21 TYPE 4 ADC TYPE 2 VCC TYPE 4 SDC TYPE 1 SDC 22TYPE 4 ADC TYPE 2 VCC TYPE 3 SDC TYPE 2 SDC 23 TYPE 4 ADC TYPE 4 SDCTYPE 3 SDC TYPE 3 DSC 24 TYPE 4 ADC TYPE 4 SDC TYPE 2 VCC TYPE 1 VCC

TABLE 4 A B C D 1 TYPE 1 ADC TYPE 1 DSC TYPE 2 SDC TYPE 2 CVC 2 TYPE 1ADC TYPE 1 CVC TYPE 3 DSC TYPE 4 DSC 3 TYPE 1 ADC TYPE 2 DSC TYPE 2 VCCTYPE 4 SDC 4 TYPE 2 ADC TYPE 1 SDC TYPE 2 DSC TYPE 1 CVC 5 TYPE 2 ADCTYPE 2 SDC TYPE 1 VCC TYPE 4 DSC 6 TYPE 2 ADC TYPE 2 CVC TYPE 3 SDC TYPE4 SDC 7 TYPE 3 ADC TYPE 1 VCC TYPE 1 DSC TYPE 2 DSC 8 TYPE 3 ADC TYPE 3DSC TYPE 1 SDC TYPE 2 CVC 9 TYPE 3 ADC TYPE 4 DSC TYPE 3 SDC TYPE 2 VCC10 TYPE 4 ADC TYPE 3 SDC TYPE 1 DSC TYPE 1 CVC 11 TYPE 4 ADC TYPE 2 VCCTYPE 1 SDC TYPE 2 SDC 12 TYPE 4 ADC TYPE 4 SDC TYPE 1 VCC TYPE 3 DSC

As examples of the implementation of the interface conversion module 220in terms of the basic components, a first embodiment of the invention isillustrated in FIG. 5. In this embodiment, the interface conversionmodule 220 is implemented with the parallel form of the invention. Fromconfiguration 1 listed in TABLE 1, block A is the TYPE 1 ADC, block B isthe TYPE 1 CVC, block C is the TYPE 1 DSC, and block D is the TYPE 2DSC. The TYPE 1 CVC 504 is coupled to the RXI input. It receives anincoming single-ended current signal to be converted into a single-endedvoltage signal CV1. The TYPE 1 DSC 506 is coupled to the RXV+ and RXV−inputs to receive an incoming pair of differential voltage signals. TheTYPE 1 DSC 506 converts the incoming differential voltage signal pairinto a single-ended voltage signal CV2. The TYPE 2 DSC 508 is coupled tothe RXI+ and RXI− inputs to receive an incoming pair of differentialcurrent signals. The TYPE 2 DSC 508 performs a conversion of theincoming differential current signal pair to a single-ended voltagesignal CV3. The TYPE 1 ADC 502 is coupled to the RXV input. As depicted,it is also coupled to the parallel connection of the TYPE 1 CVC 504, theTYPE 1 DSC 506 and the TYPE 2 DSC 508. Note that a selection unit 510 isoptionally used to choose the input for the TYPE 1 ADC 502. In otherwords, the TYPE 1 ADC 502 selectively receives an incoming single-endedvoltage signal, the CV1 signal, the CV2 signal, or the CV3 signal as itsinput. The TYPE 1 ADC 502 then converts its input into a digital signalto be further processed by the DSP 210. Thus, the interface conversionmodule 220 supports a multi-mode interface between the baseband receiver200 and a RF IC.

In a second embodiment, the interface conversion module 220 isimplemented with the hybrid form I as shown in FIG. 6. Fromconfiguration 2 set forth in TABLE 3, block A is the TYPE 1 ADC, block Bis the TYPE 1 DSC, block C is the TYPE 2 DSC, and block D is the TYPE 2SDC. The TYPE 2 DSC 608 is coupled to the RXI+ and RXI− inputs toreceive an incoming pair of differential current signals. The TYPE 2 DSC608 performs a conversion of the incoming differential current signalpair to a single-ended voltage signal. The TYPE 2 SDC 606 is coupled tothe RXI input. The TYPE 2 SDC 606 receives an incoming single-endedcurrent signal to be converted into a pair of differential voltagesignals. The converted differential voltage signals are provided on theV+ and V− outputs of the TYPE 2 SDC 606, respectively. The TYPE 1 DSC604 is coupled to the RXV+ and RXV− inputs, as well as the TYPE 2 SDC606. The TYPE 1 DSC 604 selectively receives an incoming pair ofdifferential voltage signals or the converted pair of differentialvoltage signals to be converted into a single-ended voltage signal. Thisconverted single-ended voltage signal is provided on the V output of theTYPE 1 DSC 604. Next, the TYPE 1 ADC 602 is coupled to the RXV input,the TYPE 1 DSC 604 and the TYPE 2 DSC 608. The TYPE 1 ADC 602selectively receives an incoming single-ended voltage signal from theRXV input, the converted single-ended voltage signal from the TYPE 1 DSC604, or the converted single-ended voltage signal from the TYPE 2 DSC608. Hence, the TYPE 1 ADC 602 converts its single-ended voltage inputinto a digital output signal to be further processed by the DSP 210.

In a third embodiment, the interface conversion module 220 isimplemented with the hybrid form II as shown in FIG. 7. Fromconfiguration 4 listed in TABLE 4, block A is the TYPE 2 ADC, block B isthe TYPE 1 SDC, block C is the TYPE 2 DSC, and block D is the TYPE 1CVC. The TYPE 2 DSC 706 is coupled to the RXI+ and RXI− inputs toreceive an incoming pair of differential current signals. The TYPE 2 DSC706 performs a conversion of the incoming differential current signalpair to a single-ended voltage signal. This converted single-endedvoltage signal is provided on the V output of the TYPE 2 DSC 706. TheTYPE 1 CVC 708 is coupled to the RXI input to receive an incomingsingle-ended current signal. It performs a conversion of thesingle-ended current signal to a single-ended voltage signal that isprovided on the V output of the TYPE 1 CVC 708. Next, the TYPE 1 SDC 704is coupled to the RXV input, as well as the parallel connection of theTYPE 2 DSC 706 and the TYPE 1 CVC 708. The TYPE 1 SDC 704 selectivelyreceives an incoming single-ended voltage signal from the RXV input, theconverted single-ended voltage signal from the TYPE 2 DSC 706, or theconverted single-ended voltage signal from the TYPE 1 CVC 708. The TYPE1 SDC 704 converts its single-ended voltage input into a pair ofdifferential voltage signals. The converted differential voltage signalsare provided on the V+ and V− outputs of the TYPE 1 SDC 704,respectively. The TYPE 2 ADC 702 is coupled to the RXV+ and RXV− inputs,as well as connected to the TYPE 1 SDC 704. Finally, the TYPE 2 ADC 702selectively receives an incoming or the converted pair of differentialcurrent signals to be converted into a digital signal to be furtherprocessed by the DSP 210.

With the highly flexible multi-mode interface, the baseband receiver 200offers all necessary input modes to accommodate the most common RF ICsin the industry. It should be appreciated that the baseband receiver 200needs not enable all of the input modes at the same time. The inputmodes of the baseband receiver 200 may be digital, single-ended voltage,single-ended current, differential voltage or differential current, or acombination. When one of the input modes is chosen to interface with thedesired RF IC, the rest of the input modes have to be disabled. Theinoperative components implemented in the interface conversion module220 may enter a power-down state to prevent unnecessary powerconsumption. Furthermore, depending on practical applications, basebandtransmitters working in conjunction with the baseband receiver of theinvention are not limited to those having symmetrical design andcorresponding interface.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. To the contrary, it isintended to cover various modifications and similar arrangements aswould be apparent to those skilled in the art. Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

1.-12. (canceled)
 13. An apparatus for providing a multi-mode interfacebetween a baseband receiver and radio frequency (RF) circuitry, the RFcircuitry translating incoming RF signals to baseband for the basebandreceiver, the apparatus comprising: a first single-ended-to-differentialconverter for taking an incoming single-ended signal and outputting aconverted pair of differential signals; and an analog-to-digitalconverter for selectively taking an incoming pair of differentialsignals or the converted pair of differential signals, and outputting adigital signal to be further processed by the baseband receiver; wherebythe incoming single-ended signal and the incoming differential signalpair together form the multi-mode interface to the RF circuitry.
 14. Theapparatus as recited in claim 13 wherein the incoming single-endedsignal is a single-ended voltage signal and the firstsingle-ended-to-differential converter changes the incoming single-endedvoltage signal into a first pair of differential voltage signals as theconverted differential signal pair.
 15. The apparatus as recited inclaim 14 wherein the incoming differential signal pair is a differentialvoltage signal and the analog-to-digital converter selectively receivesthe incoming differential voltage signal pair or the first differentialvoltage signal pair to be converted into the digital signal.
 16. Theapparatus as recited in claim 15 further comprising a current-to-voltageconverter for receiving an incoming pair of differential currentsignals, performing a conversion of the incoming differential currentsignal pair to a second pair of differential voltage signals, andoutputting the second pair of differential voltage signals to theanalog-to-digital converter where the second differential voltage signalpair are selectively received to be converted into the digital signal.17. The apparatus as recited in claim 15 further comprising adifferential-to-single-ended converter for receiving an incoming pair ofdifferential current signals, performing a conversion of the incomingdifferential current signal pair to a converted single-ended voltagesignal, and outputting the converted single-ended voltage signal to thesingle-ended-to-differential converter where the converted single-endedvoltage signal is selectively received to be converted into the firstdifferential voltage signal pair.
 18. The apparatus as recited in claim15 further comprising a current-to-voltage converter for receiving anincoming single-ended current signal, performing a conversion of theincoming single-ended current signal to a converted single-ended voltagesignal, and outputting the converted single-ended voltage signal to thesingle-ended-to-differential converter where the converted single-endedvoltage signal is selectively received to be converted into the firstdifferential voltage signal pair.
 19. The apparatus as recited in claim15 further comprising a second single-ended-to-differential converterfor receiving an incoming single-ended current signal, performing aconversion of the incoming single-ended current signal to a second pairof differential voltage signals, and outputting the second pair ofdifferential voltage signals to the analog-to-digital converter wherethe second differential voltage signal pair are selectively received tobe converted into the digital signal.
 20. The apparatus as recited inclaim 13 further comprising an input terminal to directly receive anincoming digital signal translated by the RF circuitry such that themulti-mode interface includes the incoming single-ended signal, theincoming differential signal pair and the incoming digital signal.